AR Shadow in AR Foundation not working first time Android

Hello all,

I am sorry if this sounds like a noob question.

I am using Ar Foundation 4.0.0
Universal RP 7.1.8
Unity 2019.3.7f1

I am experiencing a strange issue with shadows in AR Foundation. The scene is developed from the UX example and I place a custom prefab.

The prefab includes a shader which allows me to have AR shadows while using the URP.

When I start the app the first time, I have to give permission to use the camera. The the app opens but when I place the prefab, there is no shadow.

If I reopen the app this time the shadow would appear.

is the issue linked to the permission request? What is preventing the shader from working correctly on first launch?

Any help would be appreciated!

Here is the shader code

Code (CSharp):

1. Shader "Custom/AR Shadows"
2. {
3.     Properties
4.     {
5.  
6.     }
7.  
8.     SubShader
9.     {
10.         Tags { "LightMode" = "ForwardBase" "RenderType"="Opaque" "Queue"="Geometry+1" "ForceNoShadowCasting"="True"  }
11.         LOD 300
12.  
13.         Pass
14.         {
15.             Name "AR Shadows"
16.             Tags
17.             {
18.                 "LightMode" = "UniversalForward"
19.             }
20.  
21.             Blend SrcAlpha OneMinusSrcAlpha
22.             ZWrite On
23.             Cull Off
24.  
25.             HLSLPROGRAM
26.             //#pragma prefer_hlslcc gles
27.             #pragma exclude_renderers d3d11_9x
28.             #pragma target 2.0
29.  
30.             // -------------------------------------
31.             // Material Keywords
32.             #pragma shader_feature _ALPHATEST_ON
33.             #pragma shader_feature _ALPHAPREMULTIPLY_ON
34.  
35.             // -------------------------------------
36.             // Lightweight Pipeline keywords
37.             #pragma multi_compile _ _MAIN_LIGHT_SHADOWS
38.             #pragma multi_compile _ _MAIN_LIGHT_SHADOWS_CASCADE
39.             #pragma multi_compile _ _ADDITIONAL_LIGHTS_VERTEX _ADDITIONAL_LIGHTS
40.             #pragma multi_compile _ _ADDITIONAL_LIGHT_SHADOWS
41.             #pragma multi_compile _ _SHADOWS_SOFT
42.  
43.             // -------------------------------------
44.             // Unity defined keywords
45.             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
46.             #pragma multi_compile _ LIGHTMAP_ON
47.  
48.             //--------------------------------------
49.             // GPU Instancing
50.             #pragma multi_compile_instancing
51.  
52.             #pragma vertex HiddenVertex
53.             #pragma fragment HiddenFragment
54.  
55.             #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
56.             #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
57.  
58.             struct Attributes
59.             {
60.                 UNITY_VERTEX_INPUT_INSTANCE_ID
61.                 float4 positionOS   : POSITION;
62.             };
63.  
64.             struct Varyings
65.             {
66.                 float4 positionCS   : SV_POSITION;
67.                 float4 shadowCoord  : TEXCOORD0;
68.             };
69.  
70.             Varyings HiddenVertex(Attributes input)
71.             {
72.                 Varyings output = (Varyings)0;
73.  
74.                 UNITY_SETUP_INSTANCE_ID(input);
75.                 UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(output);
76.  
77.                 VertexPositionInputs vertexInput = GetVertexPositionInputs(input.positionOS.xyz);
78.  
79.                 output.shadowCoord = GetShadowCoord(vertexInput);
80.                 output.positionCS = vertexInput.positionCS;
81.  
82.                 return output;
83.             }
84.  
85.             half4 HiddenFragment(Varyings input) : SV_Target
86.             {
87.                 UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(input);
88.  
89.                 half s = MainLightRealtimeShadow(input.shadowCoord);
90.  
91.                 return half4(0, 0, 0, 1 - s);
92.             }
93.             ENDHLSL
94.         }
95.  
96.         UsePass "Universal Render Pipeline/Lit/DepthOnly"
97.     }
98.  
99.     FallBack "Hidden/InternalErrorShader"
100. }
101.  

It was modified from this link.

Many Thanks!